Sediment samples at the core of a model project

Dozens of core samples, taken from sediment around Cockburn Sound, will play a crucial role in the creation of a model of the area’s ecosystem to help inform environmental assessment of the proposed port.

The work, being done as part of the WAMSI Westport Marine Science Program, involved divers collecting three sediment cores from 12 sites and scientists analysing them at a specially created laboratory nearby.

The project is being run by Professor Bradley Eyre from Southern Cross University and Professor Matthew Hipsey, from The University of Western Australia.

Professor Eyre said the tubes of sediment and water were set up in a laboratory, in the garage of a beachside home, where conditions simulated in situ temperature and changing light conditions between night and day, at the sediment surface.

“Some analysis is best done when we have fresh samples, so we wanted to avoid any delays,” Professor Eyre said.

“Other samples will be sent back to the Southern Cross University campus near Byron Bay, which has the only instrumentation in Australia for some of the analyses.”

The 12 locations in the Sound, represent different types of shallow and deep sediments including muds, seagrass meadows, and sandy areas.

“In the laboratory, we were measuring the flux of oxygen and nutrients in and out of sediment including nutrients such as ammonia and phosphate,” Professor Eyre said

“Some of the tubes contained sediment with seagrass growing in it.

“We are also measuring a critical process in the sediments called denitrification.

“Denitrification is a natural process by which ecosystems such as Cockburn Sound can remove nitrogen.”

“It is a really important cleansing process but if the carbon load gets too high the process can be reduced.”

The researchers said data from the sediment testing would underpin new water quality modelling of the Cockburn Sound ecosystem.

“The data complements other key experimental data being collected as part of the WAMSI Westport Marine Science Program on the chemical and biological conditions, allowing the development of Cockburn Sound Integrated Ecosystem Model platform to help manage the system,” Professor Hipsey said

“What we are measuring will reflect what is happening currently in the Sound and when used alongside the modelling we will be able to predict what will happen under future scenarios.”

Plastic’s everywhere – so how do we stop it contaminating samples? 

Microplastics researchers need to think about everything from the jackets they wear in the field and their sampling containers to laboratory washing up methods to avoid contamination, according to a visiting biology professor who runs a plastics testing laboratory in the United States.

Dr Brian Walker, from Fairfield University in Fairfield Connecticut, told a recent workshop at The University of Western Australia’s Indian Ocean Marine Research Centre there had been a big growth in microplastics studies since 2010 as concerns mounted about the vast volume of plastics breaking up and being eaten by land and marine life.

“There is evidence these plastics are now affecting human health,” Dr Walker said.

“They can also be a vessel for bringing organisms such as viruses and neurotoxins into the body.”

The workshop was organised by Dr Belinda Cannell, from UWA’s Oceans Institute. UWA is one of the Western Australian Marine Science Institution’s partner organisations.

Dr Walker, who has worked for more than 20 years with penguins in Argentina, told the group he had developed some best practices for fieldwork and laboratory analysis to help ensure the highest standards for microplastics research. He said avoiding sample contamination involved scrutiny of every part of the process from the field to laboratory.

“When I have worked with collected penguin excrement, I try to get it as fresh as possible so it’s less likely to pick up micro or nano plastics in the environment although this isn’t always possible,” he said.

Dr Cannell, who is investigating microplastics in little penguins in Western Australia, said the seabirds’ nests can create challenges.

“Little penguins do not nest on the surface, so we don’t usually get to see a penguin defecating, so we scrape the samples from the ground,” Dr Cannell said.

Both researchers take care to avoid contamination by wearing cotton, rather than latex, gloves and retrieving samples with metal, not plastic, tools.

Dr Walker advises researchers to wear clothes made of natural fibres as much as possible because fabrics such as Polarfleece, which is widely used in cold climate garments, often shed synthetic fibres.

“When it’s raining, cotton is not an option so after one field trip where I wore a raincoat, I removed some of its fibres for testing to check they hadn’t got into the samples from the field,” he said.

“Back in my laboratory we hand wash glass sample jars with double filtered water and don’t use the dishwasher because of the plastic hoses.”

“The jars are always covered with foil rather than plastic and we even check to make sure there is no film on the foil.

“I can’t stress enough the importance of stopping contamination.”

Dr Walker said a new infrared microscope, he’d bought with the help of a grant, would speed up and improve the laboratory’s process for identifying microplastics on filters.

Coral reefs vital for ocean life

A quarter of all marine species depends on coral reefs but these vital parts of the oceans’ ecosystem are at risk from acidification, pollution, over-fishing and rising water temperatures.

The University of Western Australia’s PhD candidate Josh Bonesso spoke to high school students recently about the significance of coral reefs, as part of the Western Australian Marine Science Institution’s Thinking Blue outreach program. Josh was a finalist in the Student Scientist of the Year category in this year’s Premier’s Science Awards for his innovative research on coral reef islands. He’s also a keen science communicator.

“Coral reefs are nursery grounds for fish, they’re important too for megafauna and the building of coral reef islands that provide nesting areas for many species of seabirds and turtles,” Josh said.

“So, while coral reefs aren’t a large component of the ocean, about 25 percent of marine species rely on them directly and indirectly.”

Josh explained to the Year 12 students how coral reefs formed over thousands of years but that higher-than-normal temperatures and storm events caused by climate change threatened the survival of many coral varieties, particularly fragile branching corals. Mound corals were generally more resilient, but Josh said it was important for reefs not to become homogenous.

“At 34 degrees a species of branching coral, Acropora aspera, exerts a stress response and experiences bleaching.

“We know less about how these corals cope with stress at temperatures below bleaching, at around 32 degrees, and how this impacts their recovery from injury following storm events.”

“But experiments have been done in tanks at that lower temperature where the tops of coral branches are snipped off, to replicate storm damage, and they haven’t grown back,” Josh said.

Thinking Blue is WAMSI’s education outreach program which is designed to educate students about marine science and inspire them to do further studies in the field.

Josh is a PhD candidate at UWA’s Oceans Institute. He did his undergraduate science degree at La Trobe University and initially studied alpine and conservation ecology. But he told the students after a field trip to the Heron Island Research Station on the Great Barrier Reef, he ‘fell in love with coral reefs’.

You can watch Josh’s lecture here.